Biomineralization-inspired magnetic nanoflowers for sensitive miRNA detection based on exonuclease-assisted target recycling amplification

Biomineralization-inspired magnetic hybrid nanoflowers were prepared facilely, and capture probes were easily immobilized on the obtained nanoflowers without tedious processing. Based on the magnetic hybrid nanoflowers and exonuclease-assisted target recycling amplification, a fluorescence miRNA sensor was fabricated. The presence of target miRNA leads to the formation of the double-strand structure, which would then be selectively digested by the exonuclease and increase fluorescence intensity. The target miRNA can be released for recycling and signal amplification. Under optimized reaction conditions, the hybrid nanoflower-based miRNA sensor had a broad detection range from 0.001 nM to 100 nM and a limit of detection of 0.23 pM (S/N = 3). The sensitive detection of miRNA in serum was also achieved with recoveries from 94.3% to 116.1%. This work provides a new insight into the fabrication of bioconjugated materials and shows great potential in miRNA sensing.